Centrifugal pipe casting apparatus



June 19, 1934- N. F. s. RUSSELL Er AL 1,963,147

CENTRIF'UGAL PIPE CASTING APPARATUS Filed June 6, 1933 Patented June 19, 1934 UNITED STATES PATENll OFFICE berg, Edgewater Park, N. J., United States Pipe and Foundry assignors Company,

Burlington, N. J., a corporation of New Jersey Application June s, 1933, Serial No. 674,503

3 Claims.

Our invention relates'to centrifugal pipe casting apparatus and has for its object to provide such apparatus with means for building up upon the surface of the cylindrical portion of the centrifugal mold a coating of finely divided dry coating material by means of a carrier gas jet of substantially the entire length of the cylindrical portion of the mold in advance of the pouring of metal into said coated portion of the mold, and our invention is particularly, though .not exclusively, adapted for use in connection with pipe casting apparatus in which the -mold is charged with molten metal from a dump trough inserted in and extending over the cylindrical portion of the mold. v

Incur application filed October 19, 1932, Serial Number 638,480, we have described the method of coating the cylindrical portion of centrifugal molds with finely divided dry coating material by means of a 'jet of carrier gas charged with finely divided dry coating material directed against the cylindrical portion of as to build up upon said cylindrical surface a coating of the material delivered by the jet and, particularly, the method as applied to that kind of centrifugal pipe casting machine in which the molten metal is delivered to the mold through a relatively retractable runner so as to deliver the metal to'the mold in the form of a helix, the carrier gas jet being first directed against one end of the cylindrical portion of the mold in advance of the contact of the molten metal therewith and then as the pouring proceeds, being retracted through the length of the cylindrical portion of the mold at substantially the same speed-with which the runner is retracted so as to build up the coating progressively in immediate advance of the contact of the molten metal with the coated portions and in our said prior application we have pointed out that the efliciency of the coating as a retarder of heat transfer is impaired by delay in bringing the molten metal into contact with the coated portion of the mold, due no doubt to the fact that as freshly coating is made up not only of the particles of dry finely divided material but also of adsorbed films of gas surrounding the particles which have a tendency to escape on exposure to the conditions existing in the promptly covered by the molten metal. We have also in our said prior application pointed out the desirability of limiting the coating to'a thickness not materially in excess of that which will bring about a sumcient retardation of heat transfer to effect the purpose hadin view as, for exthe mold in such manner deposited upon the mold the mold if the coating is not (Cl. 2H5) ample, the avoidance of areas of chill on the outer 1 surface of the pipe and we have explained that with highly efiicient coating materials, notably, ferro-silicon, applied as a coating by means of the carrier gas jet, we have found it satisfactory to build up a coating by the distribution over the cylindrical portion of the mold of the dry finely divided material in quantity which, if evenly and compactly distributed over the cylindrical surface, would form a coating of .0003 in thickness. We have also in our said prior appli-v tion pointed out that it is not advisable to use j in forming the coating, finely divided dry coating material materially in excess of that which, under the same conditions, would form a coating of .001 in thickness and have explained that among the reasons that it is desirable to limit the thickness of the coating are that by increased thickness there is increased liability of portions of the coating becoming displaced, with the result that portions of the mold are unprotected and, therefore, liable to come in inm iediate contact with the molten metal and also that. with in--- transfer, apply to coatings which are built up upon the cylindrical mold surface by means of the apparatus which forms the subject matter of our present application.

While, for reasons that we have stated, it is advisable that the thickness of the coating deposited upon themold should be kept as thin as will make it effective to prevent the formation of a chill, particularly with regard to the quality of the casting produced and while it is true that thicker coatings are more liable to fracture than thinner coatings, we have found that in using the dump trough method of charging a coated mold with molten metal there is less tendency for the occurrence of fractures and displacement of the coating from the impact of the molten metal than is the case where the molten metal is supplied through a retracting runner and that in such a, method of casting it is practical to use a considerably thicker coating than where the metal is supplied through a retracting runner.

In our co-pending' applications, filed June 6, 1933 Serial Numbers 674,502 and 674,506 we have, in case Serial Number 674,502 described and ticles' of finely divided dry coating materialagainst; successive .areas of the cylindrical portion of the mold-until the entire cylindrical surface is coated from end to end and then charging the so coated portion of the mold with molten metal; also the preferred method ofapplying the coating to the entire cylindrical surface of the mold in advance of the pouring of the molten metal by which the coating is applied to successive, adjacent longitudinal areas of the mold by means of a charged carrier gas jet of a length equal to that of the cylindricalportion of the mold. We have also in our said method application specifically describedthe preferred method step of charging the molten metal to the cylin-' drical portion of a mold previously coated with finely divided dry coating material, as stated above, by means of a dump trough delivering its charge of molten metal to thecoated cylindrical portion of the rotating mold substantially simultaneously to successive areas of themold extending through the entire length of the cylindrical portion of the mold and in our co-pending application, Serial Number 674,506 we have described and claimed pipe casting apparatus adapted for use in the practice of the method steps indicated. above involving the. combination with a centrifugal pipe mold of a carrier gas jet nozzle of a length substantially equal to that of thecylindrical portion of the mold and adapted to deliver a jet of carrier gas of a length equal to that of the cylindrical portion of the mold over they entire length of 'said cylindrical portion of the mold and in our said application we have also described and claimed-the combination with such an elongated carriergas jet nozzle of means for charging the jet issuing from the nozzle with finelydivided dry coating material after the issuance of the jet from the nozzle, such means consisting of an elongated receptacle for a charge of the coating material located and arranged so as to deliver its charge to the carrier gas jet after it issues from the nozzle and before its contact with the mold, said receptacle, as well as the jet nozzle, being preferably supported on a dump trough for molten metal from which the metal can be delivered promptly after the coating of the mold.

The invention which we seek to protect by our present application consists essentially of that special construction involving the combination with the centrifugal mold of a carrier gas jet nozzle adapted to deliver a jet of carrier gas to the .entire length of the .mold with a tiltable recep- 60 tacle for a charge of finely divided 'dry coating material and so located with regard to the jet .nozzle that, when tilted, the receptacle will feed its charge of coating material to the jet issuing from the jet nozzle along its entire length and a suitable support for the receptacle and nozzle, preferably a dump trough, for the delivery of molten metal. These and other features of our invention will be best understood as described in connection with the drawing which illustrates a centrifugal pipe casting apparatus provided with our improvements and in which Figure 1 is an elevation,.partly in central longitudinal section through the mold, of a pipe casting apparatus involving on improvements.

showing the mold in longitudinal section and the location ,in the mold of the dump trough for molten metal, the tiltable receptacle for the charge of coating material and the jet nozzle indicating how the tiltable receptacle is pivotally 80 delivering or feeding its contents to the jet of carrier gas issuing from the nozzle.

A indicates a housingfor the mold which may serve as a water receptacle if water is used as a cooling medium, through which extends a rotatable metal mold indicated at B, the ends of which extend through the walls of the housing and are supported thereby. C indicates a motor connected by gearing, indicated at C to rotate the mold. Dindicates a carriage suitably supported on a track, as indicated at D to move longitudinally in alignment with the mold. E indicates a dump trough supported on the carriage D and adapted, when its carriage is moved toward the mold, to extend into the mold so as to extend over and slightly beyond the cylindrical portion of the mold. F indicates a'handle lever secured to the end of the dump trough and by means of which it can be tilted to discharge its contents. G indicates a counter-weight extending from the .rear portion of the carriage D to balance the weight of the charged dumping trough. H, H, etc., are brackets secured, as shown, to the side of the dumping trough E, opposite to the edge of the trough over which the metal is poured and pivotally supporting, as shown, the jet nozzle J which is provided 'with holes, indicated at J so located and arranged as to deliver a substantially continuous jet of the carrier gas over the entire length of the cylindrical portion of the mold.

In order to insure an approximately even delivery of carrier gas, it is advisable that the gas should remain under pressure in the nozzle J while it is being delivered through the holes J and this can be secured by making the aggregate area of the delivery holes J considerably less than the cross-sectional area of the nozzle J and, of course, by a suitable regulation of the delivery of gas under pressure to the nozzle. In practice we find it. advisable that the aggregate area of the outlet openings should be about onehalf of the cross-sectional area of the nozzle.

An unperforated extension J of the jet nozzle is suitably supported on the carriage D in bearings indicated at D and a lever J is secured to this extension of the jet nozzle for giving it a partial rotation in its bearings. The end of the extension J is shown as connected by a flexible hose K, connected with a source of compressed gas, indicated at K and at K we have indicated a valve for opening and closing the connection between the gas receptacle and the jet nozzle. I indicates a tiltable receptacle or trough which, as 'indicated,'is made tiltable by being secured to the jet nozzle J, being, as shown, at-

tached to the jet nozzle adjacent to its pouring lip I This receptacle is of a length substantially equal to that ofthe cylindrical portion of the mold and to the length of the jet of carrier gas 1 issuing from the nozzle. At L we have indicated the charge'of coating material with which the 76 Figure 2 is 9. fragments. y isometric elevation receptacle I is charged and at M, Fig. 3, we have l50 indicated the jet of carrier gas issuing from the nozzle J.

In operation, the carriage D is moved away from the mold so. as to retract therefrom the dump trough E and tiltable receptacle 1, which are then charged respectively with molten metal and with finely divided dry mold coating material. The carriage is then moved toward the mold until the dump trough E, the receptacle I and the nozzle J extend over the entire length of the cylindrical portion of the mold and the mold being set in rotation the valve K is opened so as to feed the jet nozzle J with the carrier gas which issues from itin an elongated jet of substantially the length of the cylindrical portion of the mold. The lever J is then actuated to tilt the jet nozzle and tiltable receptacle attached thereto so that the charge of dry finely divided coating material is fed from the receptacle into the jet issuing from the jet nozzle and deposited by the jet upon the rotating cylindrical surface 01 the mold, the deposit being, of course, made progressively to adjacent longitudinal areas of this portion of the mold. This operation is continued until the coating material in the tilting receptacle I is exhausted and results in building up upon the surface of the mold a continuous coating which, for reasons we have explained, should, for the best results be as thin as is found effective to produce the desired retardation in transfer of heat from the molten metal to be charged into the mold. When the coating of the mold has been thus effected, the valve K is closed and the dump trough E 15 then tilted as by the lever F to feed its charge of molten metal on to the rotating cylindrical portion of the coated mold and, for the best results, the charging of the molten metal into the mold should follow as quickly as possible the deposit of the coating upon the surface of the mold.

It will be understood that the special construction shown in the drawing and above described is that which we believe embodies our invention in its most practical form but it should be understood that, except where our claims are specifically limited to the special form indicated, they are not to be understood as limited to this special construction as our invention can obviously be applied in various modified forms of construction.

Having now described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. In combination with a centrifugal pipe mold having a cylindrical section, an elongated carrier gas nozzle adapted, in operative position, to extend substantially over the cylindrical portion of the pipe mold and to deliver a jet of carrier gas extending from end to end of said cylindrical portion, a tiltable receptacle for dry finely divided mold coating material adapted in operative position to extend substantially over the cylindrical portion of the mold and so located'with reference to the jet nozzle that when tilted it will pour its contents into the carriergas jet issuing from the nozzle, means for supporting the jet nozzle and tiltable receptacle in operative positions within the mold, means for supplying the jet nozzle with carrier gas and means for cutting off the supply of carrier gas.

2. Apparatus as called for in claim 1, in which the jet nozzle is attached to the tiltable receptacle adjacent to its pouring lip.

3. In a centrifugal pipe casting apparatus comprising a centrifugal mold and a dump trough for molten metal extending in operative position substantially over the cylindrical portion of the mold, the combination therewith of an elongated tiltable receptacle for finely divided dry mold coating material supported on the dump trough and, when the dump trough is in operative position, extending substantially over the entire length of the cylindrical portion of the mold, a carrier gas jet nozzle also supported by the dump trough and adapted, when the dump trough is in operative position, to project a jet of carrier gas over the entire length of the cylindrical portion of the mold, said jet nozzle being located adjacent to the pouring lip of the tiltable receptacle and so directed that the jet issuing therefrom will be contacted by coating material when the receptacle is tilted, means for supplying the jet nozzle with carrier gas and means for cutting 01! the supply of carrier gas to the nozzle.

NORMAN F. S. RUSSELL. FREDERICK C. LANGENBERG.- 

